Suggest you study M.W.
Evans, "O(3) Electrodynamics," in
Modern Nonlinear Optics, Second Edition,

Ed. M. W. Evans,
Wiley, 2001, Part II, p. 79-267.

There you can find
everything you wish to find about O(3) EM.

Also, by M.W. Evans in
the same volume, see "The Link Between The Sachs and O(3) Theories of
Electrodynamics," p. 469; and "The Link between the Topological Theory
of Ranada and Trueba, the Sachs Theory, and O(3) Electrodynamics," p.
495.